This invention relates to a circular fluorescent lamp with an integrated ballast and starting device and a base for connection to a supply voltage, the ballast and starting device being arranged in a housing which is secured inside the space formed by the circular fluorescent lamp, and the base being connected to the housing concentrically with the circular fluorescent lamp.
Various fluorescent lamps of this type are known. Constructions in which the housing surrounds the fluorescent lamp itself, known from West German DE-OS No. 28 19 550, have a character of a luminaire. The resulting enlarged lamp unit is in most cases unsuited for use in existing fittings.
The circular fluorescent lamp described in U.S. Pat. No. 2,697,777, the entire contents of which are incorporated herein by reference, has a coaxial ellipsoidal housing for the ballast and starting device to which a screw base is affixed, the housing being arranged inside the space formed by the fluorescent lamp. The fluorescent lamp rests on wire brackets which are attached to the housing. This construction may be operated only base down.
U.S. Pat. No. 4,109,303, the entire contents of which are incorporated herein by reference, describes a lamp unit comprising one or several concentrically arranged circular fluorescent lamps. Each of the fluorescent lamps is supported by a square base plate of transparent plastic material whose four corners are bent around the fluorescent lamp in clip-like manner. The ballast is affixed to the base plate inside the space formed by the innermost lamp. The screw base is arranged on the flat backside of the base plate. The lamp unit does not have a closed housing; the lamp wiring is free and visible.
The main object of the present invention is to provide a compact lamp unit which is easy to handle and which may be inserted in existing fittings.